Rab18’s Weblog

After looking at the way the 4026 works it was decided to replace this with the 4511 BCD to 7-segment decoder. The problem with the 4026 was that with this circuit design, each of the digits on the display would require one 4026 ic making four in total, where as with the 4511 BCD only one would be needed for all four digits. This will simplify the pcb design. Also the 4026 resets and counts through from zero every time you change the number. This is done fast enough for the human eye not to notice, but this way still is not an efficient way of displaying the time. 
The 4511 BCD decoder converts BCD into a numerical display. As with the 4026 ic the 4511 also drives a common cathode seven segment display. To illuminate one segment, the corresponding output has to be high. The 4511 has four BCD inputs, input a, input b, input c and input d. These inputs are feed high (1) and low(0) this binary code is then converted by the 4511 into numbers on the display.